Reference Guide for the Model XM128 ISDN Digital Modem
6-10 ISDN Overview
V.110 ISDN Communications
This section describes how to set up and configure your Model XM128 modem with the V.110
Protocol.
Answering a V.110 Call
After you set the proper V.110 communication mode, there is no ne ed to conf igure the ISDN mode
to the protocol of an incoming call. If the device is set to auto-answer, the Model XM128 modem
determines the correct protocol to use by examining the data coming in from the remote site.
Otherwise, this determination takes place after an answering command is issued.
One exception to this process is when the ISDN data call is carried through speech bearer. In this
case, you need to make an MSN entry for the phone number from which you are expecting the
data-over-speech-bearer call to be coming for X.75 protocol. Use AT&ZI1=n. Refer to “Data over
Speech Channel” on page6-7 for details.
To allow the Model XM128 modem to answer the incoming call, you need to set S0 to a value
greater than 0 (in other words. ATS0=1). The Model XM128 modem answers the call and uses
asynchronous to synchronous conversions to and from the DTE. If S0 is not set (S0=0), the DCE
reports RING and also makes an audible ring notification.
Making a V.110 Call
Before an ATDIxxx command is issued to dial out, make sure that your Model XM128 modem is
in the asynchronous mode (AT&M0). Use the commands in Table 6- 6 to configure V.110 ISDN
communication.
Table6-6. V.110 configuration commands
AT Command Description
ATB10 User rate follows DTE speed
ATB13 User rate = 2400bps
ATB14 User rate = 4800bps
ATB15 User rate = 9600bps
ATB16 User rate = 14400bps
ATB17 User rate = 19200bps
ATB18 User rate = 38 .4 Kbps
ATB19 User rate = 57.6 Kbps (Japanese version only)